1. Field of the Invention
This invention relates to a vibration-isolating apparatus for supporting a vibration-generating body, mainly used for supporting an engine of an automobile or the like.
2. Description of the Related Art
Following vibration-isolating apparatuss are known as an engine mount or the like, which supports a vibration generating body such as an engine of an automobile while preventing the transmission of the vibration of the vibration-generating body to a vehicle body. One of the known vibration-isolating apparatuses comprises an upper metal fitting having a mounting bolt which is mounted on a vibration-generating-body side; a lower metal fitting having bolts which are mounted on a vehicle-body side; and a vibration-isolating base body connecting the upper and lower metal fittings and formed of an elastic material having rubber-like elasticity. Another one of the known vibration-isolating apparatus further comprises an insert metal fitting embedded in the vibration-isolating base body for improving rigidity in a direction perpendicular to an axial direction, in which axial direction the upper and lower metal fittings moves toward and away from each other, while maintaining the vibration-isolating function in the axial direction.
Various insert metal fittings have been proposed (for example, see JP-A-1998-047423(JP-A-10047423) or Japanese Patent Publication Unexamined No.10-47423(1998). Sizes of screw heads of the upper mounting bolts have been varied according to the magnitude of vibration which differs depending on the type of vehicle; or the screw heads have been fixedly secured on a tubular member by means of press-fitting, caulking or welding; to name a few.
Varying the shape of the screw heads requires a plurality of bolts to meet each specification. Thus, the handling of parts becomes cumbersome. On the other hand, fixedly securing of the bolt on the tubular member requires application of adhesive. also on inner surface of the tubular member prior to vulcanization, because the tubular member have to be adhered by the vulcanization to the vibration-isolating base body formed of the elastic material. However, since the tubular member is literally tubular in shape, it is difficult to coat the inner surface of the tubular member with the adhesive. Further, at the time of vulcanization, it is difficult to assure the inflow of injected rubber onto the inner circumferential surface of the tubular member. Accordingly, there arises a possibility of producing defective products.
In view of the above, vigorous research has been made to obtain an insert metal fitting which enables a simple construction, lower manufacturing cost and a satisfactory state of adhesion after the vulcanization. As a result, we have found as follows. It is advantageous that the insert metal fitting is formed by bending a plate or sheet in an approximately U-shape so that the insert metal fitting opens in one direction among the directions perpendicular to an axial direction. By this formation, the application or spreading of an adhesive onto the inner surface of the metal fitting can be carried out easily. Moreover, rubber material which constitutes the vibration-isolating base body can be easily injected into the inside of the insert metal fitting, thus giving rise to the satisfactory state of adhesion after the vulcanization.
In short, a vibration-isolating apparatus according to the present invention comprises upper and lower metal fittings; a vibration-isolating base body connecting the upper and lower metal fittings and formed of an elastic material having rubber-like elasticity; and an insert metal fitting embedded in the vibration-isolating base body; the insert metal fitting being formed of a plate or sheet bent in an approximately U-shape and having an upper end portion thereof attached to the upper metal fitting.
In above, the insert metal fitting is attached to the lower surface of the upper metal fitting. In this case, the insert metal fitting having approximate U-shape may open either upwardly or downwardly. To be more specific, for example, the insert metal fitting of one aspect comprises: a pair of flat side-plate portions; and a connecting portion connecting the upper ends of the side-plate portions and having a through hole for a mounting bolt; the connecting portion being clamped between the upper metal fitting and a screw head of the mounting bolt which bolt is upwardly inserted into the through hole from vibration-isolating base-body side of the connecting portion.
On the other hand, for example, the insert metal fitting of another aspect comprises: a pair of flat side-plate portions; a connecting portion connecting the lower ends of the side-plate portions; and a flange portion formed on upper ends of the side-plate portions in such a manner as the upper ends are outwardly bent, the flange portions being fixedly secured to the lower surface of the upper metal fitting.
In both cases, the insert metal fitting laterally opens in one direction among the directions perpendicular to the axial direction. Thus, the coating of the inner surface of the insert metal fitting with an adhesive can be carried out easily; and the rubber material which constitutes the vibration-isolating base body can be easily injected into the space within the insert metal fitting. Further, the lateral direction to which the insert metal fitting opens perpendicularly to the axis can be freely set. The clamping position or the welding position of the insert metal fitting onto the upper metal fitting can be varied corresponding to the spring constant required in the direction perpendicular to the axis. Further, by changing the width of the plate or sheet or the length of the side-plate portions, a desired spring constant can be easily obtained. In addition to these advantages, in case of the insert metal fitting formed in an approximately U-shape which opens downwardly, the mounting thereof can be carried out more easily compared to cases where the insert metal fitting is welded, fixed by caulking or press-fitted onto the upper metal fitting.
Thickness of the plate or sheet for forming the insert metal fitting is not particularly limited and may be suitably selected corresponding to the required rigidity. For instance, by providing reinforcing ribs to the pair of side-plate portions, even the insert metal fitting formed of a thin plate or sheet has a required rigidity. The reinforcing ribs may be positioned on the side edges or on the central areas of the insert metal fitting.
As for injecting position or injecting direction of the rubber material with respect to the insert metal fitting, although they are not particularly limited, it is advantageous that the rubber injecting direction is set parallel to main surfaces of the side-plate portions of the insert metal fitting because the inflow of the injected rubber material is further facilitated. In particular, it is advantageous that a rubber injection port is disposed to correspond a space between a pair of side-plate portions with respect to a direction perpendicular to the side-plate portions, because the inflow of the rubber material into a space between a pair of side-plate portions is facilitated. Further, it is advantageous to form one or more holes in each of the side-plate portions or the connecting portion, because the flow of the rubber material is improved so that the integral formation between the insert metal fitting and the rubber member is further improved.
The insert metal fitting having the above-mentioned construction is applicable to various kinds of vibration-isolating apparatus. For example, the insert metal fitting is applicable to a liquid-filled vibration-isolating apparatus. This vibration-isolating apparatus further comprises a diaphragm associated with the lower metal fitting; a liquid chamber defined by the vibration-isolating base body and the diaphragm; a partition dividing the liquid chamber into a main liquid chamber and a sub liquid chamber; and an orifice formed in the partition and communicating the main liquid chamber with the sub liquid chamber.